Arrangement for temperature monitoring and regulation

ABSTRACT

To measure and regulate temperature, a temperature measuring resistor ( 3 ) and a control element ( 2 ) are accommodated in one layer as metallization on a substrate ( 1 ). The printed conductors of the temperature measuring resistor ( 3 ) and of the control element ( 2 ) are arranged in close proximity to one another.

BACKGROUND INFORMATION

[0001] The present invention is directed to a system for measuring and regulating temperature, having a temperature measuring resistor and a control element.

[0002] For highly accurate temperature measurement that is stable over a long period of time, metal film resistors, in particular platinum thin-film resistors, have been used due to the relatively strong temperature-dependence of the electric resistivity of platinum and its high chemical and physical resistance. The properties of platinum resistors for use in industrial temperature measurement are described in DIN IEC 751.

[0003] A common manufacturing method which is also used in large-scale industrial production is the vapor deposition of a metal layer, e.g., platinum, on ceramic substrates, which allows accurate control of the layer thickness and thus of the resistance for a given structure. The surface of this thin film can be subsequently shaped as desired by masking and etching. In order to obtain an absolute calibration and highly accurate resistance, the etched resistor structure must be trimmed. This trimming is performed using laser ablation, for example.

[0004] The above-described method provides highly accurate temperature measuring resistors that are stable over a long period of time. The smallest surface resistor shapes and structures can be realized using manufacturing processes similar to those in the semiconductor industry. Using this manufacturing method, the shape of the metal film resistor on the surface of the substrate is relatively freely selectable. In order to arrive at the smallest possible shapes for a given desired resistance, and to enable the use of simple trimming algorithms, the resistors are usually given a wave-shaped structure.

[0005] Electrical contacting of the thin-film resistors is effected via contact wires soldered, bonded, or welded to the contact surfaces.

[0006] For temperature regulation, the combination of a temperature measuring resistor with a control element is needed. This control element may be a Peltier element or, for an application requiring long-term stability, a resistance heating element, for example.

ADVANTAGES OF THE INVENTION

[0007] The measures recited in Claim 1 allow highly stable and highly accurate temperature regulation of preferably planar components. Because the temperature measuring resistor is adjacent to the control element on a common substrate with the respective printed conductors in close proximity, the temperature difference between the temperature measuring resistor and the control element is minimized. This allows maximum absolute accuracy to be achieved in measuring the temperature of the control element.

[0008] Furthermore, the cost of implementing a temperature regulating system is reduced because of the smaller number of components due to the integration of the control element and the temperature measuring resistor on a common planar substrate. This is important in particular for an automated planar hybrid assembly.

[0009] The control element and the temperature measuring resistor are produced in a common manufacturing process, which results in reduced costs in addition to technical advantages.

[0010] Conventional production methods for metal thin-film resistors may be used for manufacturing the proposed system.

[0011] The essence of the present invention is the combination of two metal film resistors adjacent to one another on a preferably planar substrate. The function of the control element is assigned to one of the metal film resistors, while the second metal film resistor is used as a temperature measuring resistor.

[0012] The advantages of the above-described combination of metal film resistors are:

[0013] the minimized physical distance between control element and temperature measuring resistor minimizes the temperature difference between the two metal film resistors. Maximum accuracy in measuring the absolute temperature of the control element is thus achieved;

[0014] the time between a change in temperature of the control element and of the temperature measuring resistor is minimized due to the minimized physical distance. This increases the stability of electronic regulation which uses one of the metal film resistors as the control element and the other one as the temperature measuring resistor (minimal delay);

[0015] the integration of two functions in a single component reduces the space requirement for control element and temperature measuring resistor (temperature sensor of a temperature regulating system). This may be the only possible implementation of a highly stable temperature regulation for very small components having edge lengths of a few millimeters;

[0016] the integration of two functions using the same technology on a single substrate reduces the manufacturing complexity and thus the costs;

[0017] the absence of a joint between the control element and the temperature measuring resistor increases the long-term stability of the temperature measurement and temperature regulation. This is very important in particular under extreme environmental conditions (wide temperature ranges, vacuum, radiation emissions, aggressive chemicals);

[0018] the combination of a control element and a temperature measuring resistor designed as a planar component is compatible with the planar hybrid assembly method, which allows easy integration of such a component using automated manufacturing methods.

[0019] Due to the system according to Claim 2, the printed conductors of the temperature measuring resistor and the control element are subjected to exactly the same temperature variation, which contributes to accurate temperature measurement and regulation.

[0020] The measures recited in Claims 3, 4, and 8 result in a negligible temperature gradient between component and temperature measuring resistor, and there is no delay between manipulated variable and actual value, which might result in reduced regulating system stability. Claim 5 allows the control element to be designed as the temperature measuring resistor with the only difference that it is heated by the application of a heating current.

[0021] According to Claim 6, the temperature measuring resistor and the control element may be manufactured in a single operation by vapor deposition.

[0022] By applying an insulating protective film on the two printed conductors according to Claim 7, greater freedom is obtained in joining the control element/temperature measuring resistor combination to a component to be tempered.

[0023] Claim 9 makes a simple calibration method available, in particular in order to achieve characteristic values of the temperature measuring resistor that conform to the standards.

[0024] Claim 10 points out an advantageous possible application of the system according to the present invention for resonators.

DRAWING

[0025] Exemplary embodiments are explained with reference to the drawing.

[0026]FIG. 1 shows a conventional system for temperature regulation;

[0027]FIG. 2 shows a plan view of a system according to the present invention;

[0028]FIG. 3 shows a section through the system according to FIG. 2;

[0029]FIG. 4 shows a plan view of a modified system according to the present invention;

[0030]FIG. 5 shows a section through the system according to FIG. 4.

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

[0031] Before describing the actual system according to the present invention, we shall describe a conventional system for temperature measurement and temperature regulation. FIG. 1 shows such a conventional system. The temperature of a component 6 is to be measured and regulated. A temperature sensor 3 is provided on the top of side of component 6. The bottom of component 6 is provided with a control element 2 in the form of a heating resistor, which was applied to a substrate 1 and is covered with an insulating layer 4.

[0032] The physical distance between control element 2 and temperature sensor 3 results in a temperature gradient between sensor and control element and therefore in a corresponding inaccuracy in the temperature measurement. In addition, the physical distance results in a delay between manipulated variable and actual value, which causes reduced stability of the regulating system.

[0033]FIG. 2 illustrates an exemplary embodiment of a system according to the present invention. Temperature measuring resistor 3 and control element 2 are applied to a substrate 1 in a common layer as a metal plating. An aluminum oxide substrate is suitable as a substrate. Strip-like printed conductors of temperature measuring resistor 3 and control element 2 are situated adjacent to one another and run essentially in parallel to one another in a wave-shaped pattern. Control element 2 preferably has a metal resistor layer made of the same material as the metal resistor layer of the temperature measuring resistor. The only differences between the control element and the temperature measuring resistor are that an electric voltage is applied to the resistor layer of control element 2 to heat it, and different resistances are used depending on the desired control characteristic, for example, 10 to 100 Ω for control element 2 and 1000 Ω for temperature measuring resistor 3.

[0034] The two resistor layers are applied to substrate 1 using known methods, e.g., by vapor deposition. The resistor layers of temperature measuring resistor 3 and control element 2 are electrically contacted via contacts 5, which may be designed as solderable, bondable, or weldable contacts. Passivating protective layer 4 may be applied to thin metal resistor layers 2 and 3 for protection. This layer allows greater freedom in joining the heating element/temperature sensor combination to a component 6 to be tempered (see sectional view in FIG. 5).

[0035] An electric voltage is applied to the contacts of control element 2 (heating resistor). The current and the voltage across the heating resistor produces a heating power with which component 6 and substrate 1 are warmed. The temperature in the plane of the substrate surface is measured using the temperature measuring resistor. A definite resistance is established as a function of the resistor temperature (for platinum metal film resistors see DIN IEC 751). The resistance is measurable with high accuracy using a bridge circuit at zero current.

[0036] The shape and position of metal resistors 2 and 3 are virtually freely selectable within the plane, because the resistors are manufactured using the above-mentioned vapor deposition technology. Only the respective masks must be produced, and it must be ensured that no overlap occurs between the printed conductors of control element 2 and temperature measuring resistor 3.

[0037] This degree of freedom in design makes it possible to adjust the shape of the resistors to the geometry of a given component 6 to be tempered. The adaptation of the heating resistor geometry to the component may be used for homogeneous heating of the component. The measuring resistor geometry may be thus adapted to make possible the measurement of the average temperature of component 6.

[0038] In order to achieve characteristic values of the measuring resistor that conform to the standards, it is also possible to apply adjusting structures on the substrate. These adjusting structures may be located inside or outside the base surface of component 6 on substrate 1.

[0039] Due to the configuration of the heating resistor and measuring resistor in one plane, the temperature of this plane can be measured with high accuracy. To ensure that the temperature of component 6 exactly corresponds to that of the measuring plane, the component must be thermally insulated from the rest of the environment. It must also be ensured that component 6 itself is not a heat source. If these conditions are not met, there may be a temperature difference between component 6 and temperature measuring resistor 3.

[0040] While the arrangement illustrated in FIGS. 2 and 3 has, a wave-shaped pattern of the printed conductors of temperature measuring resistor 3 and control element 2, the arrangement of the printed conductors of temperature measuring resistor 3 and control element 2 in FIGS. 4 and 5 is triangular, because component 6 directly mounted on the layer of the printed conductors of temperature measuring resistor 3 and control element 2, i.e., on layer 4 which covers them, also has a triangle-shaped design.

[0041] Possible components 6 which may be needed for high-precision temperature regulation include optical (laser crystals) or electrical (quartz) resonators. The intrinsic frequency of such resonators depends on their geometric dimensions and their thermal expansion, and thus on their temperature. Therefore, the control of the absolute temperature of these components is essential for high-precision absolute frequency stabilization. 

What is claimed is:
 1. A system for measuring and regulating temperature, comprising a temperature measuring resistor and a control element, having the following features: the temperature measuring resistor (3) and the control element (2) are applied to a substrate (1) as a metal plating in a single layer; the printed conductors of the temperature measuring resistor (3) and of the control element (2) are in close proximity to one another.
 2. The system as recited in claim 1, wherein the printed conductors of the temperature measuring resistor (3) and control element (2) have a strip-like design and run essentially in parallel to one another.
 3. The system as recited in claim 1 or 2, wherein the shapes of the printed conductors of the temperature measuring resistor (3) and control element (2) are adjusted to the geometry of the component to be heated.
 4. The system as recited in one of claims 1 through 3, wherein the geometry of the printed conductor of the temperature measuring resistor (3) is selected so as to allow the measurement of the average temperature of the component (6) to be tempered.
 5. The system as recited in claims 1 through 4, wherein the control element (2) is designed as a heatable resistor.
 6. The system as recited in claims 1 through 5, wherein the printed conductors of the temperature measuring resistor (3) and of the control element (2) are made of a metal layer vapor deposited on the substrate (1).
 7. The system as recited in one of claims 1 through 6, wherein the printed conductors of the temperature measuring resistor (3) and of the control element (2) are covered with an insulating layer (4).
 8. The system as recited in one of claims 1 through 7, wherein the component (6) to be tempered is directly mounted on the layer of the printed conductors of the temperature measuring resistor (3) and of the control element (2), i.e., on the insulating layer (4) covering them.
 9. The system as recited in one of claims 1 through 8, wherein adjusting structures are provided on the substrate (1) for the printed conductor of the temperature measuring resistor (3).
 10. A use of the system as recited in one of claims 1 through 9 for temperature regulation of optical or electrical resonators. 